Particle reducing method and film deposition method

ABSTRACT

A particle reducing method includes a step of supplying a first gas to a vacuum chamber in which a susceptor, formed by an insulating object and the surface of which is provided with a substrate mounting portion, is rotatably provided; a step of generating plasma from the first gas by supplying high frequency waves to a plasma generating device provided for the vacuum chamber; and a step of exposing the substrate mounting portion, on which a substrate is not mounted, to the plasma while rotating the susceptor.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on Japanese Priority Application No.2012-010162 filed on Jan. 20, 2012, the entire contents of which arehereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to a particlereducing method and a film deposition method.

2. Description of the Related Art

A film deposition method in which a thin film is formed on asemiconductor wafer (hereinafter, referred to as a “wafer”) is known asone of methods of manufacturing a semiconductor integrated circuit. Afilm deposition apparatus which is used for the film deposition methodincludes a sealable chamber, a susceptor provided in the chamber onwhich a wafer is to be mounted, a source gas supplying unit whichsupplies a source gas onto the wafer mounted on the susceptor, and anevacuation device which is connected to the chamber and evacuates thesource gas.

When forming a thin film on a wafer using such a film depositionapparatus, there is a problem that a deposited object is also formedinside the chamber to cause particles when the deposited object ispeeled. In order to solve this problem, a method of removing thedeposited object inside the chamber has been examined (see PatentDocument 1, for example).

Here, in accordance with the miniaturization of the circuit componentsformed on the wafer, it is required to further improve the filmthickness uniformity and controllability of the film thickness of thethin film. In order to respond to such a requirement, a film depositionmethod so-called “Atomic Layer Deposition” (ALD) or “Molecular LayerDeposition” (MLD) is expected.

For this film deposition method, a film deposition apparatus as followsmay be used. The film deposition apparatus includes a susceptor, onwhich plural wafers are to be mounted, rotatably provided in a vacuumchamber and, a first reaction gas supplying unit which is capable ofsupplying a first reaction gas onto the plural wafers which are mountedon the susceptor, and a second reaction gas supplying unit which isprovided apart from the first reaction gas supplying unit in arotational direction of the susceptor and is capable of supplying asecond reaction gas which can react with the first reaction gas. Withthis film deposition apparatus, when the first reaction gas and thesecond reaction gas are respectively supplied from the first reactiongas supplying unit and the second reaction gas supplying unit whilerotating the susceptor, the first reaction gas and the second reactiongas are alternately adsorbed onto the surfaces of the wafers on thesusceptor so that thin films, which are a result of the surfacereaction, are formed on the wafers, respectively.

Specifically, in an ALD apparatus provided by the inventors of thepresent invention (see Patent Document 2), the first reaction gas andthe second reaction gas can be sufficiently separated from each other sothat the deposited object (residue) is hardly deposited inside thevacuum chamber. Therefore, generation of the particles due to thedeposited object deposited inside the vacuum chamber can be sufficientlylowered.

However, recently, the requirement to reduce the particles has beenincreased so that a method of further reducing the particles isrequired.

[Patent Document]

[Patent Document 1] Japanese Laid-open Patent Publication No.2008-159787

[Patent Document 2] Japanese Patent No. 4661990

SUMMARY OF THE INVENTION

The present invention is made in light of the above problems, andprovides a particle reducing method capable of reducing particles causedby a susceptor on which a substrate is to be mounted.

According to an embodiment, there is provided a particle reducing methodincluding a step of supplying a first gas to a vacuum chamber in which asusceptor, formed by an insulating object and the surface of which isprovided with a substrate mounting portion, is rotatably provided; astep of generating plasma from the first gas by supplying high frequencywaves to a plasma generating device provided for the vacuum chamber; anda step of exposing the substrate mounting portion, on which a substrateis not mounted, to the plasma while rotating the susceptor.

According to another embodiment, there is provided a film depositionmethod using a film deposition apparatus including a vacuum chamber inwhich a susceptor, formed by an insulating object and the surface ofwhich is provided with a substrate mounting portion, including a filmdeposition process step in which a substrate is mounted on the substratemounting portion and a film is deposited on the substrate; and aparticle reducing process step performed before or after the filmdeposition process step, in which particles in the vacuum chamber arereduced without mounting the substrate on the substrate mountingportion, the particle reducing process step including, a step ofsupplying a first gas to the vacuum chamber; a step of generating plasmafrom the first gas by supplying high frequency waves to a plasmagenerating device provided for the vacuum chamber; and a step ofexposing the substrate mounting portion, on which a substrate is notmounted, to the plasma while rotating the susceptor.

Note that also arbitrary combinations of the above-describedconstituents, and any exchanges of expressions in the present invention,made among methods, devices, systems and so forth, are valid asembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

FIG. 1 a cross-sectional view of an example of a film depositionapparatus of an embodiment;

FIG. 2 is a perspective view showing an inside structure of a vacuumchamber of the film deposition apparatus shown in FIG. 1;

FIG. 3 is a schematic top view showing an example of the vacuum chamberof the film deposition apparatus shown in FIG. 1;

FIG. 4 is a partial cross-sectional view of an example of the filmdeposition apparatus shown in FIG. 1;

FIG. 5 is a partial cross-sectional view of an example of the filmdeposition apparatus shown in FIG. 1

FIG. 6 is a schematic cross-sectional view of an example of a plasmagenerating device provided in the film deposition apparatus shown inFIG. 1;

FIG. 7 is another schematic cross-sectional view of the plasmagenerating device provided to the film deposition apparatus shown inFIG. 1;

FIG. 8 is a schematic top view of the plasma generating device providedto the film deposition apparatus shown in FIG. 1;

FIG. 9 is a flowchart showing an example of a particle reducing methodof the embodiment;

FIG. 10 is a schematic view showing a susceptor (substrate mountingportion) which is charged by the plasma generating device of the filmdeposition apparatus shown in FIG. 1; and

FIG. 11 is a flowchart showing an example of a film deposition method ofthe embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described herein with reference to illustrativeembodiments. Those skilled in the art will recognize that manyalternative embodiments can be accomplished using the teachings of thepresent invention and that the invention is not limited to theembodiments illustrated for explanatory purposes.

It is to be noted that, in the explanation of the drawings, the samecomponents are given the same reference numerals, and explanations arenot repeated. Further, drawings are not intended to show relative ratiosof a component or components.

First, a mechanism in which particles are generated in a substrateprocessing apparatus (such as the above described ADL apparatus) isexplained.

The present inventors have found that the particles may be generated bythe following reason(s) after extensive research.

The susceptor included in the above described ALD apparatus may bemanufactured by forming a concave portion on which a wafer can bemounted on a circular plate made of quartz, for example. Specifically, acircular plate made of quartz having a size (diameter) large enough forhaving a predetermined numbers of wafers mounted thereon is prepared.Then, plural concave portions are formed on the surface of the circularplate by grinding, etching or the like. Usually, when a component madeof quartz is grinded, etched or the like, the component is treated withanneal at a predetermined temperature in order to flatten the surface orthe like. However, when manufacturing the susceptor, annealing may notbe performed in order to prevent deformation or the like of thesusceptor by the heat. Thus, the bottom surface of the concave portionremains as a rough surface.

Further, each of the concave portions is formed to have a slightlylarger diameter, for example, 2 to 4 mm larger, than that of the waferin order to have the wafer easily mounted therein. Thus, when thesusceptor is started to be rotated after the wafers are mounted on theconcave portions, respectively, the wafers move within the respectiveconcave portions so that the backside surface of each of the wafersrasps with the bottom surface of the respective concave portion. Here,as the bottom surface of the concave portion is the rough surface whilethe backside surface of the wafer is polished to be a mirror finishedsurface, the rough surface of the concave portion is polished togenerate particles of quartz.

When such particles of quartz exist at the bottom surface of each of theconcave portions, the particles of quartz may be scattered when thewafers are mounted on the concave portions or the wafers are removedfrom the concave portions, respectively, to cause contamination wherethe particles of quartz adhere onto the surfaces of the wafers.

Thus, it is necessary to remove such particles of quartz in order toreduce the particles adhere onto the surfaces of the wafers. However,the particles of quartz are generated every time the wafers are mountedon the respective concave portions of the susceptor provided in thevacuum chamber. Thus, it is hard to remove the particles by chemicalsolution or the like. Further, if the particles of quartz are includedin the small rough surface of the concave portion, it is hard to removethe particles by the purging gas or the like.

(Film Deposition Apparatus)

First, a film deposition apparatus for performing a film depositionmethod of the embodiment is explained.

With reference to FIG. 1 to FIG. 3, a film deposition apparatus includesa vacuum chamber 1 having a substantially flat circular shape, and asusceptor 2 provided in the vacuum chamber 1 and has a center ofrotation at the center of the vacuum chamber 1. The vacuum chamber 1includes a chamber body 12 having a cylindrical shape with a bottomsurface, and a ceiling plate 11 placed on the upper surface of thechamber body 12. The ceiling plate 11 is detachably placed on thechamber body 12 via a sealing member 13 (FIG. 1) such as an O-ring in anairtight manner.

The susceptor (turntable) 2 is made of quartz, for example. Thesusceptor 2 is attached to the cylindrical shaped core unit 21 at itscenter portion. The core unit 21 is fixed to the upper end of the rotaryshaft 22 which extends in the vertical direction. The rotary shaft 22 isprovided to penetrate the bottom portion 14 of the vacuum chamber 1 andits lower end is attached to the driving unit 23 that rotates the rotaryshaft 22 (FIG. 1) around a vertical direction. The rotary shaft 22 andthe driving unit 23 are housed in the tubular case body 20 whose uppersurface is open. The case body 20 is attached to a lower surface of thebottom portion 14 of the vacuum chamber 1 via a flange portion providedat its upper surface in an airtight manner so that the inner atmosphereof the case body 20 is isolated from the outside atmosphere.

As shown in FIG. 2 and FIG. 3, plural (five in this case) circularconcave portions 24 are provided at a front surface of the susceptor 2along a rotating direction (circumferential direction) shown by an arrowA for holding plural semiconductor wafers (which will be simply referredto as “wafers” hereinafter) W, respectively. Here is an example wherethe wafer W is shown to be placed in one of the concave portions 24 inFIG. 3 for an explanatory purpose.

Each of the concave portions 24 is formed to have a slightly largerinner diameter, for example, 4 mm larger, than the diameter of the waferW, and a depth substantially equal to the thickness of the wafer W.Thus, when the wafer W is mounted in the respective concave portion 24,the surface of the wafer W and the surface of the susceptor 2 (where thewafer W is not mounted) become almost the same height.

As will be explained later, each of the concave portions 24 are providedwith three, for example, through holes, through which lift pins (neitherare shown in the drawings) for supporting a back surface of therespective wafer W and lifting the wafer W penetrate.

FIG. 2 and FIG. 3 are views showing an inside structure of the vacuumchamber 1. The ceiling plate 11 is not shown in FIG. 2 and FIG. 3 so asto simplify explanation.

As shown in FIG. 2 and FIG. 3, a reaction gas nozzle 31, a reaction gasnozzle 32, separation gas nozzles 41 and 42, and a gas introductionnozzle 92, which are made of quartz, for example, are provided above thesusceptor 2. For the example shown in FIG. 3, the gas introductionnozzle 92, the separation gas nozzle 41, the reaction gas nozzle 31, theseparation gas nozzle 42, and the reaction gas nozzle 32 are aligned inthis order from a transfer port 15 (which will be explained later) in aclockwise direction (the rotation direction of the susceptor 2 as shownby an arrow A in FIG. 3) with a space therebetween in a circumferentialdirection of the vacuum chamber 1. Gas introduction ports 92 a, 31 a, 32a, 41 a, and 42 a (FIG. 3) which are base portions of the nozzles 92,31, 32, 41, and 42, respectively, are fixed to an outer peripheral wallof the fixing chamber body 12 so that these nozzles 92, 31, 32, 41, and42 are introduced into the vacuum chamber 1 from the outer peripheralwall of the vacuum chamber 1 to extend in a radial direction andparallel to the surface of the susceptor 2.

As simply shown by a dotted line for an explanatory purpose in FIG. 3, aplasma generating device 80 (plasma generating source) is provided abovethe gas introduction nozzle 92. The plasma generating device 80 isexplained later.

In this embodiment, the reaction gas nozzle 31 is connected to asupplying source (not shown in the drawings) of a Si (silicon)containing gas as a first reaction gas via a pipe, a flow controller andthe like (not shown in the drawings). The reaction gas nozzle 32 isconnected to a supplying source (not shown in the drawings) of anoxidation gas as a second reaction gas via a pipe, a flow controller andthe like (not shown in the drawings). The separation gas nozzles 41 and42 are connected to supplying sources (not shown in the drawings) ofnitrogen (N₂) gas as a separation gas via pipes and flow controllervalves and the like, respectively.

In this embodiment, organo-aminosilane gas is used as the Si containinggas, and O₃ (ozone) gas is used as the oxidation gas.

The reaction gas nozzles 31 and 32 are provided with plural gasdischarge holes 33 (see FIG. 4) which are facing downward to thesusceptor 2 along the longitudinal directions of the reaction gasnozzles 31 and 32 with a 10 mm interval, respectively, for example. Anarea below the reaction gas nozzle 31 is a first process area P1 inwhich the Si containing gas is adsorbed onto the wafers W. An area belowthe reaction gas nozzle 32 is a second process area P2 in which the Sicontaining gas which is adsorbed onto the wafers W at the first processarea P1 is oxidized.

Referring to FIG. 2 and FIG. 3, the ceiling plate 11 is provided withtwo protruding portions 4. The protruding portions 4 are attached to thebackside surface of the ceiling plate 11 to be protruded toward thesusceptor 2, as will be explained later, in order to form separationarea D with the separation gas nozzles 41 and 42. Each of the protrudingportions 4 has substantially a sector top view shape where the apex isremoved in an arc shape. For each of the protruding portions 4, theinner arc shaped portion is connected to an inner protruding portion 5(which will be explained later) and the outer arc shaped portion isformed to extend along an inner peripheral surface of the chamber body12 of the vacuum chamber 1.

FIG. 4 shows a cross-section of the vacuum chamber 1 along a concentriccircle of the susceptor 2 from the reaction gas nozzle 31 to thereaction gas nozzle 32. As shown in FIG. 4, the protruding portion 4 isfixed to the lower surface of the ceiling plate 11. Thus, there areprovided a flat low ceiling surface 44 (first ceiling surface) formed asthe lower surface of the protruding portion 4 and flat higher ceilingsurfaces 45 (second ceiling surface) which are higher than the lowceiling surface 44 and formed at outboard sides of the low ceilingsurface 44 in the circumferential direction. The low ceiling surface 44has substantially a sector top view shape where the apex is removed inan arc shape.

Further, as shown in the drawings, the protruding portion 4 is providedwith a groove portion 43 at a center in the circumferential direction.The groove portion 43 is formed to extend in the radius direction of thesusceptor 2. The separation gas nozzle 42 is positioned within thegroove portion 43. Although not shown in FIG. 4, the separation gasnozzle 41 is also positioned within a groove portion 43 provided in theother protruding portion 4. The reaction gas nozzles 31 and 32 areprovided in spaces below the high ceiling surfaces 45, respectively. Thereaction gas nozzles 31 and 32 are provided in the vicinity of thewafers W apart from the high ceiling surfaces 45, respectively. Here,for an explanatory purpose, a space below the high ceiling surface 45where the reaction gas nozzle 31 is provided is referred to as “481” anda space below the high ceiling surface 45 where the reaction gas nozzle32 is provided is referred to as “482” as shown in FIG. 4.

The separation gas nozzle 42 (and similarly for the separation gasnozzle 41) is provided with plural gas discharge holes 42 h formed alongthe longitudinal direction of the separation gas nozzle 42 with apredetermined interval (10 mm, for example).

The low ceiling surface 44 provides a separation space H (separationarea D), which is a small space, with respect to the susceptor 2. Whenthe N₂ gas is provided from the separation gas nozzle 42, the N₂ gasflows toward the space 481 and the space 482 through the separationspace H. At this time, as the volume of the separation space H issmaller than those of the spaces 481 and 482, the pressure in theseparation space H can be made higher than those in the spaces 481 and482 by the N₂ gas. It means that between the spaces 481 and 482, theseparation space H provides a pressure barrier.

Further, the N₂ gas flowing from the separation space H toward thespaces 481 and 482 functions as a counter flow against the Si containinggas from the gas first process area P1 and the oxidation gas from thesecond process area P2. Thus, the Si containing gas from the firstprocess area P1 and the oxidation gas from the second process area P2are separated by the separation space H. Therefore, mixing and reactingof the Si containing gas with the oxidation gas are prevented in thevacuum chamber 1.

The height h1 of the low ceiling surface 44 above an upper surface ofthe susceptor 2 may be appropriately determined based on the pressure ofthe vacuum chamber 1 at a film deposition time, the rotational speed ofthe susceptor 2, and a supplying amount of the separation gas (N₂ gas)in order to maintain the pressure in the separation space H higher thanthose in the spaces 481 and 482.

The ceiling plate 11 is further provided with the inner protrudingportion 5 at its lower surface to surround the outer periphery of thecore unit 21 which fixes the susceptor 2. The inner protruding portion 5is continuously formed with the inner portions of the protrudingportions 4 and has a lower surface which is formed at the same height asthose of the low ceiling surfaces 44, in this embodiment.

FIG. 1 is a cross-sectional view taken along an I-I′ line in FIG. 3, andshowing an area where the ceiling surface 45 is provided. FIG. 5 is apartial cross-sectional view showing an area where the ceiling surface44 is provided.

As shown in FIG. 5, the protruding portion 4 having a substantiallysector top view shape is provided with an outer bending portion 46 atits outer peripheral end portion (at an outer peripheral end portionside of the vacuum chamber 1) which is bent to have an L-shape to facean outer end surface of the susceptor 2. The outer bending portion 46,similar to the protruding portions 4, suppresses a flow of reactiongasses from both sides of the separation areas D to prevent mixing ofthe reaction gasses. As the protruding portions 4 are provided on theceiling plate 11 which is detachably attached to the chamber body 12.Thus, there is a slight space between the outer periphery surface of theouter bending portion 46 and the chamber body 12. The space between theinner periphery surface of the outer bending portion 46 and an outersurface of the susceptor 2, and the space between the outer peripherysurface of the outer bending portion 46 and the chamber body 12 may be asize same as the height h1 (see FIG. 4) of the low ceiling surface 44with respect to the upper surface of the susceptor 2, for example.

The inside perimeter wall of the chamber body 12 is provided to extendin a vertical direction to be closer to the outer peripheral surface ofthe outer bending portion 46 at the separation area D. However, otherthan the separation area D, as shown in FIG. 1, for example, the insideperimeter wall of the chamber body 12 is formed to have a concaveportion outside of a portion facing the outer end surface of thesusceptor 2 toward the bottom portion 14. Hereinafter, for anexplanatory purpose, the concave portion, having a substantiallyrectangular cross-sectional view, is referred to as an “evacuationarea”.

Specifically, a part of the evacuation area which is in communicationwith the first process area P1 is referred to as a first evacuation areaE1, and a part of the evacuation area which is in communication with thesecond process area P2 is referred to as a second evacuation area E2. Asshown in FIG. 1 to FIG. 3, a first evacuation port 610 and a secondevacuation port 620 are respectively provided at the bottom portions ofthe first evacuation area E1 and the second evacuation area E2. In thisembodiment, the evacuation areas are provided to be positioned outsidethe outer periphery of the susceptor 2. It means that the firstevacuation port 610 and the second evacuation port 620 are provided tobe positioned outside the outer periphery of the susceptor 2.

The first evacuation port 610 and the second evacuation port 620 areconnected to vacuum pumps 640, which are vacuum evacuation units, viaevacuation pipes 630, respectively, as shown in FIG. 1. The referencenumeral 650 is a pressure regulator in FIG. 1.

The heater unit 7 is provided at a space between the susceptor 2 and thebottom portion 14 of the vacuum chamber 1 as shown in FIG. 1 and FIG. 5.The wafers W mounted on the susceptor 2 are heated by the heater unit 7via the susceptor 2 to a temperature (450° C., for example) determinedby a process recipe. A ring cover member 71 is provided at a lowerportion side of the outer periphery of the susceptor 2 in order toprevent gasses from being introduced into the space below the susceptor2 by partitioning atmosphere from a space above the susceptor 2 to theevacuation areas E1 and E2 and atmosphere in which the heater unit 7 ispositioned.

As shown in FIG. 5, the cover member 71 includes an inner member 71 awhich is provided to face the outer edge portion and the further outerportion of the susceptor 2 from a lower side, and an outer member 71 bwhich is provided between the inner member 71 a and an inner wallsurface of the chamber body 12. The outer member 71 b is provided toface the outer bending portion 46, which is formed at an outer edgeportion at lower side of each of the protruding portions 4 in theseparation areas D. The inner member 71 a is provided to surround theentirety of the heater unit 7 below the outer end portion (and at aslightly outer side of the outer end portion) of the susceptor 2.

The bottom portion 14 of the vacuum chamber 1 closer to the rotationcenter than the space where the heater unit 7 is positioned protrudesupward to be close to the core unit 21 to form a protruded portion 12 a.There is provided a small space between the protruded portion 12 a andthe core unit 21. Further, there is provided a small space between aninner peripheral surface of the bottom portion 14 and the rotary shaft22 to be in communication with the case body 20. A purge gas supplyingpipe 72 which supplies N₂ gas as the purge gas to the small space forpurging is provided in the case body 20. The bottom portion 14 of thevacuum chamber 1 is provided with plural purge gas supplying pipes 73(only one of the purge gas supplying pipes 73 is shown in FIG. 5) whichare provided with a predetermined angle interval in the circumferentialdirection below the heater unit 7 for purging the space where the heaterunit 7 is provided. Further, a cover member 7 a is provided between theheater unit 7 and the susceptor 2 to prevent the gas from beingintroduced into the space where the heater unit 7 is provided. The covermember 7 a is provided to extend from an inner peripheral wall (uppersurface of the inner member 71 a) of the outer member 71 b to an upperend portion of the protruded portion 12 a in the circumferentialdirection. The cover member 7 a may be made of quartz, for example.

The film deposition apparatus further includes a separation gassupplying pipe 51 which is connected to a center portion of the ceilingplate 11 of the vacuum chamber 1 and provided to supply N₂ gas as theseparation gas to a space 52 between the ceiling plate 11 and the coreunit 21. The separation gas supplied to the space 52 flows through asmall space between the inner protruding portion 5 and the susceptor 2to flow along a front surface of the susceptor 2 where the wafers W areto be mounted to be discharged from an outer periphery. A space 50 iskept at a pressure higher those of the space 481 and the space 482 bythe separation gas. Thus, the mixing of the Si containing gas suppliedto the first process area P1 and the oxidation gas supplied to thesecond process area P2 by flowing through the center area C can beprevented by the space 50. It means that the space 50 (or the centerarea C) can function similarly as the separation space H (or theseparation area D).

Further, as shown in FIG. 2 and FIG. 3, a transfer port 15 is providedat a side wall of the vacuum chamber 1 for allowing the wafers W, whichare substrates, to pass between an external transfer arm 10 and thesusceptor 2. The transfer port 15 is opened and closed by a gate valve(not shown in the drawings). Further, lift pins, which penetrate theconcave portion 24 to lift up the respective wafer W from a backsidesurface, and a lifting mechanism for the lift pins (both are not shownin the drawings) are provided at a respective portion below thesusceptor 2. Thus, the respective wafer W is passed between the externaltransfer arm 10 and the concave portion 24 of the susceptor 2, which isa mounting portion, at a place facing the transfer port 15.

Next, the plasma generating device 80 is explained with reference toFIG. 6 to FIG. 8. FIG. 6 is a schematic cross-sectional view of theplasma generating device 80 taken along the radius direction of thesusceptor 2. FIG. 7 is a schematic cross-sectional view of the plasmagenerating device 80 taken along a direction perpendicular to the radiusdirection of the susceptor 2. FIG. 8 is a schematic top view showing theplasma generating device 80. For an explanatory purpose, parts of thecomponents are not shown in the drawings.

Referring to FIG. 6, the plasma generating device 80 is made of amaterial which is permeable to high frequency waves, and is providedwith a concave portion in its upper surface. The plasma generatingdevice 80 further includes a frame member 81 which is embedded in anopen portion 11 a provided in the ceiling plate 11, a Faraday shieldplate 82 housed in the concave portion of the frame member 81 and hassubstantially a box shape whose top is opened, an insulating plate 83placed on a bottom surface of the Faraday shield plate 82, and a coilantenna 85 supported above the insulating plate 83. The antenna 85 hassubstantially an octagonal upper plane shape.

The open portion 11 a of the ceiling plate 11 is formed to have pluralstep portions, and one of the step portions is provided with a grooveportion to extend along the perimeter where a sealing member 81 a suchas an O-ring or the like is embedded. The frame member 81 is formed tohave plural step portions which correspond to the step portions of theopen portion 11 a, and when the frame member 81 is engaged in the openportion 11 a, a back side surface of one of the step portions contactsthe sealing member 81 a embedded in the open portion 11 a so that theceiling plate 11 and the frame member 81 are kept in an air-tightmanner.

Further, as shown in FIG. 6, a pushing member 81 c, which extends alongthe outer peripheral of the frame member 8 which is embedded in the openportion 11 a of the ceiling plate 11, is provided so that the framemember 81 is pushed downward with respect to the ceiling plate 11. Withthis, the ceiling plate 11 and the frame member 81 are further kept inan air-tight manner.

The lower surface of the frame member 81 is positioned to face thesusceptor 2 in the vacuum chamber 1 and a projection portion 81 b whichprojects downward (toward the susceptor 2) is provided at the perimeterat the lower surface. The lower surface of the projection portion 81 bis close to the surface of the susceptor 2 and a space (hereinafterreferred to as an inner space S) is provided by the projection portion81 b, the surface of the susceptor 2 and the lower surface of the framemember 81 above the susceptor 2. The space between the lower surface ofthe projection portion 81 b and the surface of the susceptor 2 may bethe same as the height h1 between the ceiling surface 44 with respect tothe upper surface of the susceptor 2 in the separation space H (FIG. 4).

Further, a gas introduction nozzle 92 which penetrates the projectionportion 81 b is provided in the inner space S. In this embodiment, asshown in FIG. 6, an argon gas supplying source 93 a filled with argon(Ar) gas, an oxygen gas supplying source 93 b filled with oxygen (O₂)gas and an ammonia gas supplying source 93 c filled with ammonia (NH₃)gas are connected to the gas introduction nozzle 92.

The gas introduction nozzle 92 is provided with plural gas dischargeholes 92 a formed along the longitudinal direction thereof with apredetermined interval (10 mm, for example) so that the Ar gas and thelike are discharged from the gas discharge holes 92 a.

As shown in FIG. 7, the gas discharge holes 92 a are provided to beinclined from a vertical direction with respect to the susceptor 2toward the upstream rotation direction of the susceptor 2. Thus, the gassupplied from the gas introduction nozzle 92 is discharged in adirection opposite to the rotation direction of the susceptor 2,specifically, toward a space between a lower surface of the projectionportion 81 b and the surface of the susceptor 2. With this, the flows ofthe reaction gas and the separation gas from a space below the ceilingsurface 45 which is upstream of the plasma generating device 80 towardthe inner space S along the rotation direction of the susceptor 2 can beprevented. Further, as described above, as the projection portion 81 bwhich is formed along an outer periphery of the lower surface of theframe member 81 is close to the surface of the susceptor 2, the pressurein the inner space S can be kept high by the gas from the gasintroduction nozzle 92. With this as well, the flows of the reaction gasand the separation gas toward the inner space S can be prevented.

The Faraday shield plate 82 is made of a conductive material such as ametal and is grounded, although not shown in the drawings. As clearlyshown in FIG. 8, the Faraday shield plate 82 is provided with pluralslits 82 s at its bottom portion. Each of the slits 82 s are extendingto be in substantially perpendicular relationship with the correspondinglines of the antenna 85 which has the substantially octagonal planeshape.

As shown in FIG. 7 and FIG. 8, the Faraday shield plate 82 includes twosupport portions 82 a which are provided at upper end portions to bendoutward. The support portions 82 a are supported by the upper surface ofthe frame member 81 so that the Faraday shield plate 82 is supported ata predetermined position in the frame member 81.

The insulating plate 83 is made of fused quartz, for example, has a sizeslightly smaller than that of the bottom surface of the Faraday shieldplate 82, and is mounted on the bottom surface of the Faraday shieldplate 82. The insulating plate 83 insulates the Faraday shield plate 82and the antenna 85 while passing the high frequency wave radiated fromthe antenna 85.

The antenna 85 is formed by winding a pipe made of copper three times,for example, in a substantially octagonal plane shape. With thisstructure, cooling water can be circulated in the pipe and the antenna85 is prevented from being heated to a high temperature by the highfrequency wave provided to the antenna 85. The antenna 85 is providedwith a standing portion 85 a to which a support portion 85 b isattached. The antenna 85 is maintained at a predetermined position inthe Faraday shield plate 82 by the support portion 85 b. The highfrequency power source 87 is connected to the support portion 85 b viathe matching box 86. The high frequency power source 87 is capable ofgenerating high frequency waves of 13.56 MHz, for example.

According to the plasma generating device 80 thus structured, when thehigh frequency waves are supplied to the antenna 85 from the highfrequency power source 87 via the matching box 86, the electromagneticfield is generated by the antenna 85. In the electromagnetic field, theelectric field component is shielded by the Faraday shield plate 82 sois not transmitted downward. On the other hand, the magnetic fieldcomponent is transmitted within the inner space S via the plural slits82 s of the Faraday shield plate 82. Plasma is generated by the gassessuch as the Ar gas, the O₂ gas, the NH₃ gas and the like which aresupplied to the inner space S with a predetermined flow rate ratio(mixed ratio) from the gas introduction nozzle 92 by the magnetic fieldcomponent. By such plasma, damage to a thin film formed on a wafer W, orto the components in the vacuum chamber 1 can be reduced.

As shown in FIG. 1, the film deposition apparatus of the embodimentfurther includes a control unit 100 which controls the entirety of thefilm deposition apparatus and a storing unit 101. The control unit 100may be a computer. The storing unit 101 stores a program by which thefilm deposition apparatus executes the film deposition method (as willbe explained later) under a control of the control unit 100. The programis formed to include steps capable of executing the film depositionmethod. The storing unit 101 may be a hard disk or the like, forexample. The program stored in the storing unit 101 may be previouslystored in a recording medium 102 such as a compact disk (CD), amagneto-optic disk, a memory card, a flexible disk, or the like and maybe installed in the storing unit 101 using a predetermined readingdevice.

(Particle Reducing Method)

With reference to FIG. 9 and FIG. 10, the particle reducing method ofthe embodiment in which the above described film deposition apparatus isused, is explained.

Further, in this embodiment, the following operations are performed whenthe film deposition process on all the wafers W of a single lot iscompleted, and wafers W are not mounted on the susceptor 2. Further, itis assumed that the transfer port 15 (FIG. 2 and FIG. 3) is closed by agate valve, not shown in the drawings.

First, in step S91 (FIG. 9), the vacuum chamber 1 is adjusted to be apredetermined set pressure. Specifically, the vacuum chamber 1 isevacuated by the vacuum pump 640 to the minimum vacuum level, and then,the N₂ gas (second gas) as the separation gas is discharged from theseparation gas nozzles 41 and 42 at a predetermined flow rate. At thistime, the N₂ gas is also discharged from the separation gas supplyingpipe 51 and the purge gas supplying pipes 72 and 73 at a predeterminedflow rate, respectively. With this, the vacuum chamber 1 is adjusted toa predetermined set pressure by the pressure regulator 650. Then, instep S92, the susceptor 2 is rotated at a predetermined rotationalspeed.

Subsequently, in step S93, the Ar gas as the plasma generating gas(first gas) is supplied to the inner space S at a predetermined flowrate from the argon gas supplying source 93 a via the gas introductionnozzle 92. Further, in step S94, high frequency waves with an outputpower of 700 W, for example, are provided to the antenna 85 of theplasma generating device 80 from the high frequency power source 87.With this, the plasma is generated in the inner space S.

By the rotation of the susceptor 2, when one of the concave portions 24of the susceptor 2 reaches a lower area of the plasma generating device80, the concave portion 24 is exposed to plasma formed in the innerspace S. At this time, as shown in (a) of FIG. 10, the electrons (e⁻) inthe plasma reach the bottom surface of the concave portion 24 (thesusceptor 2) faster than positive ions (ion⁺). Thus, the bottom surfaceof the concave portion 24 is negatively charged. With this, a sheatharea SR is formed above the bottom surface of the concave portion 24 asshown in (b) of FIG. 10.

When the susceptor 2 is further rotated, the concave portion 24 movesaway from a lower area of the plasma generating device 80 and the nextconcave portion 24 reaches the lower area of the plasma generatingdevice 80. Then, similarly, the bottom surface of the respective concaveportion 24 is negatively charged.

As such, when the susceptor 2 is rotated once, the bottom surfaces (thesusceptor 2) of all of the concave portions 24 are negatively chargedwhen passing through the lower area of the plasma generating device 80.Thereafter, in step S95, the particle reducing method of the embodimentis finished when supplying of the high frequency waves from the highfrequency power source 87 is terminated, as well as the supplying of theAr gas from the gas introduction nozzle 92 is terminated. The susceptor2 may be rotated twice or more.

As described above, the concave portions 24 are formed by grinding oretching the susceptor made of quartz. Thus, there may be fine scrapes atthe bottom surface. When the wafers W are mounted on the respectiveconcave portions 24, and the susceptor 2 is rotated, the wafers W movein the respective concave portions 24 so that the backside surface ofeach of the wafers rasps with the bottom surface of the respectiveconcave portion. In such a case, the bottom surface of the concaveportion 24 is easily grinded compared with the backside surface of thewafer W and has a flat mirror finished surface. As a result, theparticles of quartz are generated. When the particles adhere to thebottom surface of each of the concave portions 24, the particles may bescattered when the wafers W are mounted on the concave portions 24 orthe wafers are removed from the concave portions 24, respectively, tocause contamination where the particles adhere to the surfaces of thewafers W. Further, if the particles of quartz adhere to the backsidesurface of the wafer W, the particles may adhere to the surface ofanother wafer W adjacent to the respective wafer W, for example, in awafer carrier in which the wafers W are housed. Thus, the other wafer Wis also contaminated.

Thus, it is necessary to remove the particles of quartz adhered to thebottom surface of each of the concave portions 24 in order to reduce thecontamination of the wafers W. However, as the particles of quartz aregenerated when the bottom surface of the concave portion 24 rasps withthe backside surface of the respective wafer W, the particles of quartzmay be adhered to the bottom surfaces of the concave portions 24 byreversed polarities by triboelectric charging. Further, the particles ofquartz may be included in the fine rough surface remained on the bottomsurface of the concave portion 24. Thus, it is hard to remove theparticles of quartz by, for example, a purging gas or the like. Further,the susceptor 2 is provided in the vacuum chamber and the particles aregenerated when the backside surface of the wafer W and the bottomsurface of the respective concave portion 24 of the susceptor 2 raspswith each other, it is hard to remove the particles of by washing thesusceptor 2.

However, according to the particle reducing method of the embodiment, byexposing the bottom surfaces of the concave portions 24 (the susceptor2) to plasma, as shown in (b) of FIG. 10, both the bottom surface of theconcave portion 24 and the particles P which adhere to the bottomsurface are negatively charged. Thus, as shown in (c) of FIG. 10, arepulsive force is generated between the bottom surface of the concaveportion 24 and the particles P so that the particles P are easilyremoved from the bottom surface of the concave portion 24. The particlesP removed from the bottom surface of the concave portion 24 can beevacuated from the inner space S with the Ar gas and further evacuatedfrom the second evacuation port 620 (FIG. 3) with the N₂ gas (theseparation gas) which flows within the vacuum chamber 1. Thus, as aresult, the particles of quartz P at the bottom surface of the concaveportion 24 are effectively removed so that the particles generated fromthe concave portion 24 of the susceptor 2 can be reduced.

In this embodiment, as described above, the N₂ gas is discharged fromthe separation gas supplying pipe 51 and the purge gas supplying pipes72 and 73 at a predetermined flow rate, respectively. With this, a flowof a gas is generated in which the N₂ gas supplied to the separation gassupplying pipe 51 moves toward the second evacuation port 620 along thesurface of the concave portions 24 of the susceptor 2. In thisembodiment, the processes of step S93 to step S94 in FIG. 9 areperformed while such a flow of the gas is generated. Thus, the particlesof quartz P of the bottom surface of each of the concave portions 24 canbe effectively removed to reduce the particles generated from theconcave portions 24 of the susceptor 2.

Further, at this time, the separation gas is also supplied from theseparation gas nozzles 41 and 42. Thus, the pressure of the separationspace H below the low ceiling surface 44 can be made higher than thepressures at the spaces 481 and 482 to prevent the particles generatedat the concave portions 24 of the susceptor 2 from introducing into theseparation space H.

Further, according to the particle reducing method of the embodiment, itis not necessary to wash the susceptor 2 after deconstructing the vacuumchamber 1 or the like, the particles can be easily reduced with a shortperiod operation. Further, the particle reducing method of theembodiment may be performed when the wafers W are not mounted on thesusceptor 2 such as at a period after all of the wafers W of a singlelot are performed with the film deposition process and before the filmdeposition process for the wafers W of the next lot is started, or whenthe film deposition apparatus is at an idle state, for example, thethroughput of the film deposition apparatus is not lowered.

Here, when the plasma is generated by the Ar gas, quartz is notdecomposed (or etched) by the plasma. Further, even if a silicon oxidefilm is deposited on a part of the susceptor 2 other than the concaveportions 24, the silicon oxide film is not decomposed or the like by theplasma of the Ar gas. Thus, it can be considered as follows. The effectof the particle reducing method of the embodiment is not a result ofremoving the silicon oxide film deposited on the susceptor 2, but, asdescribed above, a result that the particles which adhere to the bottomsurface of each of the concave portions 24 are negatively charged, whichis the same as the respective bottom surface.

The particle reducing method explained above with reference to FIG. 9and FIG. 10 can be performed at a predetermined timing before or after afilm deposition step in which the wafers W are mounted on the susceptor2 and films are deposited on the wafers W.

FIG. 11 is a flow chart showing an example of the film depositionprocess of the embodiment. Here, first, the particle reducing method(hereinafter, referred to as a “particle reducing process”) explainedabove with reference to FIG. 9 is performed (step S102). When theparticle reducing process is finished, the wafers W are mounted on thesusceptor 2 and the film deposition process is performed (step S104).Thereafter, whether the film deposition process is continued in the filmdeposition apparatus is determined (step S106). Then, when the filmdeposition process is not finished (NO of step S106), the particlereducing process is performed again (step S102). On the other hand, whenthe film deposition process is finished (YES of step S106), the processis ended.

Here, it is not necessary to perform the particle reducing process everytime a cycle of the film deposition process is performed, and theparticle reducing process may be performed after plural cycles of thefilm deposition process are performed. Further, even for a case where itis determined that the film deposition process is not performed in stepS106, the particle reducing process may be performed before the processis finished. Further, the particle reducing process may be performed ata necessary timing between the film deposition processes by determiningthe generation status of the particles in accordance with the filmdeposition status of the deposited film, or by monitoring with a sensoror the like.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

For example, as long as it is possible to charge the bottom surface ofeach of the concave portions 24 (and the particles adhere onto therespective bottom surface) of the susceptor 2 by generated plasma, othergasses may be used instead of the Ar gas. At this time, a gas which isinactive against the susceptor 2 may be used.

Prior to step S91, a step of confirming that the wafers W are notmounted on the susceptor 2 may be performed. This confirmation may beperformed by a wafer position detection apparatus provided to the vacuumchamber 1, for example. Alternatively, this confirmation may beperformed by the above described operation by which the wafer W to bemounted on the concave portion 24 is passed to the transfer arm 10 (FIG.3) using the lift pins. Specifically, one of the concave portions 24 ispositioned to face the transfer port 15 (FIG. 3) by rotating thesusceptor 2, and then, the lift pins are moved to penetrate the throughholes to be protruded to the upper area of the susceptor 2. Then, thetransfer arm 10 (FIG. 3) is inserted into the vacuum chamber 1 via thetransfer port 15 and the lift pins are moved downward. When the wafer Wis not mounted on the concave portion 24, the transfer arm 10 cannotreceive a wafer W. This fact may be detected by a sensor provided to thetransfer arm 10, for example. With this, a fact that the wafer W is notmounted on the concave portion 24 can be detected. This operation can beperformed for all of the concave portions 24.

Further, although the particle reducing method is performed for the filmdeposition apparatus including the susceptor 2 made of quartz isexemplified, the susceptor 2 is not limited to that made of quartz, andmay be made of an insulating object such as carbon, silicon carbide(SiC) or the like. Further a susceptor 2 made of carbon and the surfaceof which is coated with SiC may be used. When the susceptor 2 made ofsuch an insulating object is exposed to the plasma, the surface isnegatively charged so that the similar advantage as explained above canbe obtained.

In the above embodiment, although the plasma generating device 80 isexemplified to adopt a so-called “inductive coupling plasma (ICP)source” including the antenna 85, the plasma generating device 80 mayadopt a capacitively coupled plasma (CCP) source.

According to the embodiment, a particle reducing method capable ofreducing particles generated by a susceptor on which a substrate is tobe mounted is provided.

Although a preferred embodiment of the particle reducing method and thefilm deposition method has been specifically illustrated and described,it is to be understood that minor modifications may be made thereinwithout departing from the spirit and scope of the invention as definedby the claims.

What is claimed is:
 1. A particle reducing method comprising: a step ofsupplying a first gas to a vacuum chamber in which a susceptor, formedby an insulating object and the surface of which is provided with asubstrate mounting portion, is rotatably provided; a step of generatingplasma from the first gas by supplying high frequency waves to a plasmagenerating device provided for the vacuum chamber; and a step ofexposing the substrate mounting portion, on which a substrate is notmounted, to the plasma while rotating the susceptor.
 2. The particlereducing method according to claim 1, wherein the susceptor is made ofquartz, and the substrate mounting portion is a concave portion formedon the susceptor.
 3. The particle reducing method according to claim 1,wherein the first gas is inactive against the insulating object.
 4. Theparticle reducing method according to claim 1, wherein the first gasincludes argon gas.
 5. The particle reducing method according to claim4, wherein the first gas includes an oxygen gas and a hydrogencontaining gas.
 6. The particle reducing method according to claim 1,wherein the plasma generating device is inductive coupling plasma. 7.The particle reducing method according to claim 1, further comprising: astep of confirming whether a substrate is mounted on the substratemounting portion of the susceptor, wherein the step of supplying thefirst gas, the step of generating the plasma, and the step of exposingthe substrate mounting portion to the plasma are performed when it isdetermined that the substrate is not mounted on the substrate mountingportion of the susceptor.
 8. The particle reducing method according toclaim 1, wherein the susceptor is provided with plural of the substratemounting portions along a circumferential direction of the susceptor atthe surface of the susceptor, the vacuum chamber includes an evacuationport which is provided outside of an outer periphery of the susceptorand a gas supplying pipe which supplies a gas from a center portion ofthe susceptor, the method further comprising: a step of generating aflow of a second gas toward the evacuation port along a surface of thesubstrate mounting portions of the susceptor by supplying the second gasfrom the gas supplying pipe, wherein the step of supplying the firstgas, the step of generating the plasma, and the step of exposing thesubstrate mounting portion to the plasma are performed while the flow ofthe second gas is generated in the step of generating the flow of thesecond gas.
 9. A film deposition method using a film depositionapparatus including a vacuum chamber in which a susceptor, formed by aninsulating object and the surface of which is provided with a substratemounting portion, comprising: a film deposition process step in which asubstrate is mounted on the substrate mounting portion and a film isdeposited on the substrate; and a particle reducing process stepperformed before or after the film deposition process step, in whichparticles in the vacuum chamber are reduced without mounting thesubstrate on the substrate mounting portion, the particle reducingprocess step including, a step of supplying a first gas to the vacuumchamber; a step of generating plasma from the first gas by supplyinghigh frequency waves to a plasma generating device provided for thevacuum chamber; and a step of exposing the substrate mounting portion,on which a substrate is not mounted, to the plasma while rotating thesusceptor.